Many people suffer from inflammatory bowel disease (IBD). IBD is a generic term used to refer to two inflammatory diseases, ulcerative colitis and Crohn's disease, and various medications are being used to treat inflammatory bowel disease. For example, mesalamine, 5-aminosalicylic acid (5-ASA) is used to treat ulcerative colitis, but is associated with various side effects. It can be absorbed as it passes through the GI tract, which can adversely affect the amount of mesalamine that reaches the lower GI tract, particularly the colon and rectum. Sulfasalazine has also been used, but is metabolized in the body to form mesalamine (5-aminosalicylic acid (5-ASA)) and sulfapyridine. Accordingly, sulfasalazine is associated with several adverse side affects, including nausea, vomiting, abdominal discomfort, male infertility, and headache. These adverse side effects are usually attributed to the activity of sulfapyridine in the GI tract, as well as that absorbed into the system. Olsalazine has also been used to treat ulcerative colitis, but is both relatively expensive to make and associated with adverse side effects including diarrhea.
Efforts have been made to minimize the side effects associated with these compounds, including efforts by the present inventors to provide compounds that, when reaching the gut mucosa, break down into one or more active compounds useful for treating inflammatory bowel disorders. Examples of such compounds are described, for example, in U.S. Pat. No. 6,583,128 to Ekwuribe et al.
It would be beneficial to provide additional synthetic methods for preparing these compounds. The present invention provides such synthetic methods.